DLP Unit 1: Intro to Gasoline Engine Repair
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What is the engine block?
the framework of the engine that houses the engine’s working components. The block includes the cylinders and the upper part of the crankcase.
Cylinder blocks are generally made up of what?
Either cast iron or aluminum.
What does the name of an engine (such as “V-8” or “In-line 4”) primarily tell you about its construction?
The engine name depicts the cylinder arrangement.
What is the primary function of the cylinder bores within the engine block?
Bores house the pistons.
How are the cylinder bores typically formed (machined) in a cast-iron engine block, as opposed to an aluminum block?
Bores are machined directly into iron blocks; in aluminum blocks, they require cast-iron sleeves.
What does the crankshaft do?
Transfers the mechanical energy from the up-and-down or reciprocating motion of the pistons to a rotary motion.
How can you distinguish a cast crankshaft from a forged crankshaft?
By looking at the parting line on the shaft. The cast crankshaft typically has a very narrow, raised parting line and the forged crankshaft has a wider, ground-off parting line.
What common contaminants or foreign matter can cause scoring and damage to the surface of the crankshaft journals?
Journals can be damaged by dirt and debris.
If the crankshaft journals have sustained only small nicks or minor marks, what is the repair process a machine shop would use to restore the surface?
Small marks in journals can be polished out.
Besides housing the main rotating and reciprocating parts, what crucial mechanical system does the engine block provide a framework for?
The engine block provides a framework for the valve train.
Name at least four essential components or passages that are included within the engine block’s basic structure.
The engine block includes: crankshaft bore cylinder bores coolant passages oil galleries
What does the valve train assembly do?
Opens and closes the valves in time with the revolutions of the crankshaft.
What are the two general types of valve train configurations found in internal combustion engines?
Two types of valve trains: • in-block • Overhead Camshaft (OHC…covered in unit 2)
What basic, strong, and durable material are most engine valves constructed from?
Most valves are solid steel.
Why must intake valves and exhaust valves be made from different types of steel materials?
Because exhaust valves are subjected to much higher temperatures than intake valves, requiring different steel compositions (e.g., carbon steel alloy for intake and stainless steel for exhaust) for durability.)
Key point: You can distinguish a cast crankshaft from a forged crankshaft by looking at the parting line on the shaft. The cast crankshaft typically has a very narrow, raised parting line and the forged crankshaft has a wider, ground-off parting line.
How can you tell the difference between an intake valve and an exhaust valve?
On an intake valve, the margin is made really thin. On an exhaust valve, the margin is thicker (because the exhaust valve gets hotter).